The family of slain police officer Bryson Anderson say he was a man who will never be replaced and has left a "legacy that will endure".

Damian Anderson delivered a statement on behalf of the family in the wake of his brother's death while on duty at Oakville in Sydney's north-west on Thursday.

"Our family cannot adequately express the devastation that follows the loss of Bryson," he said on Friday afternoon, flanked by Bryson's wife, Donna, his father Rex and his other brother, Warwick, a former officer.

"Commensurate with our sense of loss is the pride we have in a man who has given his life in the service of the people of NSW."

Detective Inspector Anderson served 26 years with the NSW police force. His brother said he was an "outstanding officer" who had been "commended for his work on many occasions".

Away from work, the 45-year-old was a "dedicated and loving" husband, father of three children, son, brother, uncle and friend.

"Bryson will never be replaced; however, he has left a legacy that will endure," Damian Anderson said. "His passing is not only a loss to his family and friends but also a loss to the people of NSW that will never be overcome."

Detective Inspector Anderson died after he was attacked with a knife when police responded to a neighbourhood dispute at Oakville, in Sydney's north-west, on Thursday afternoon. Police said there had been an extended neighbourhood dispute between two families.

An ambulance rushed Detective Inspector Anderson to hospital but he was pronounced dead a short time later.

His family thanked the officers who were with him, as well as the police ambulance and hospital staff who "worked so hard to save him".

"We would also like to thank the members of the NSW Police Force for their unwavering support, together with the family, friends and members of the community who have sent literally thousands of messages of support," Damian Anderson said.

A mother and son have been charged with the murder of the well-respected senior detective.

Mitch Barbieri, 19, and his mother Fiona, 45, opted to stay in the cells when their matter was heard briefly at Penrith Local Court on Friday morning. Neither applied for bail and it was formally refused.

Police will make an application before the court to undertake "forensic procedures", such as DNA swabs, on Mr Barbieri on December 14.

Documents before the court stated that the pair had shown "no remorse" and denied Detective Inspector Anderson's murder when they were charged by police.

Detective Inspector Anderson is the 14th officer to be killed on duty since 1980.